The Strange Realm of Infra-Red: 1

My friend Richard Kadrey introduced me to infra-red photography. Sensors on digital cameras can detect infra-red, but normally are shielded from it by a protective filter that resides as a thin layer over the chip. You can hack a camera by removing the layer, but it is easier to buy a Fuji IS-1, which is infra-red-ready. If you use a lens filter that blocks the visible frequencies, the camera displays an image that consists of infra-red transposed into the visible spectrum.

Vegetation reflects almost all light below red, and thus appears “white.” Conversely, the upper atmosphere does not refract infra-red, and thus a blue sky appears “black.” An unexpected effect is that most fabric dyes reflect infra-red, so that a crowded sidewalk appears to be populated entirely by angelic people dressed in white.

During 2007 I drove across the country and took a bunch of infra-red photographs. The Southern states looked especially good, because they contain so much vegetation.

Gorgeous shots! Wasn’t there a kerfuffle a few years ago re: infrared ability in a Sony camera? Something about pictures of people; a bit more detail of the body beneath the clothes showed through than you would expect… XRAY CAMS SNAP NUDE SHOTS the tv news talking heads foamed-at-the-mouth..?

My experience with infrared photography was with film. The film speeds available to me at a reasonable price were very slow – ISO 25 to ISO 50 or so, changing the film in the camera was a challenge (required a “black bag”), developing the film was expensive, and focusing was a challenge (infrared light passing though a lens focuses at a different point than visible light does – some SLR lenses had a separate focusing mark for infrared photography and so you’d focus normally first, then adjust the lens from the normal light mark to the infrared mark.)

Lastly, I couldn’t use my Canon EOS camera bodies because they used an infrared LED instead of a sprocket wheel to count film frames. I had to back off to my old Pentax K-1000 body.

But that’s all buggy whips and wagon wheels these days, except for the issue of lenses and focusing. Only one of my several Canon EOS lenses seems to have an infrared focusing guide, whereas most of my Pentax K-mount lenses had infrared focusing guides.

As far as I can tell, experimenting with infrared photography in the digital age is horribly expensive, requiring special camera bodies (or modifications to existing camera bodies) and special lenses. When explored infrared photography, exploration cost about $25 or so for special film and development.

Most consumer point’n’shoot cameras (and even many of the more advanced ‘prosumer’ cameras) have no IR filter; so you don’t need to buy that particular Fuji model.

To find out whether your camera has an IR filter, point a TV remote control at the camera and watch through the camera’s LCD viewfinder (NOT the optical finder, if your camera has one) while you press buttons on the remote.

If the LED on the front of the remote makes a visible flicker in the viewfinder, then you don’t have an IR filter, and you can use your camera for IR photography.

@2: Yes, and this is why the IS-1 and it’s big brother the IS Pro are the only cameras I’ve ever seen sold with a EULA. I think Fuji is afraid of the same kind of nonsense, or at least has a lawyer with an overactive imagination.

@6: Almost all digital cameras, DSLR or P&S, have an IR-cut filter. If they didn’t, you’d have red lawns in all your photos. (Just ask early Leica M8 owners)

The IR-cut filters are not perfect, so if you put an IR-pass filter on the lens, you can do IR photography but with very low sensitivity. Fine if you’re on a tripod, but useless handheld. And IS-1 or a modified camera will have much better senstivity, sometimes better than stock.

The IR remote test isn’t very meaningful, it ust shows that some IR leaks through.

A lot of people don’t realize it, but you can do some infrared work with DSLRs, but it does require long exposures.
I use an R72 filter and a tripod to do landscape shots. I happen to like night photography and that compressed time/motion thing that happens so it works well for me.
If you want to get “x-ray” shots of people though, you can pretty much forget it.

The IR blocking filter on consumer point and shoots vary in strength and cutoff frequency, so some cameras are better than others. It makes a difference when you try to fight the IR-block against your IR-pass filter, a la Zandr’s comment. Sticking an IR-pass filter composed of two layers of exposed & developed color film ends on a preexisting consumer point and shoot camera is more rewarding than spending big bucks to do infrared. I’ve experimented with various approaches to this and it’s a fascinating and easily accessible field, precisely because the cost of entry is so low.

Try taking a picture of various bills.
I had hacked my old webcam by taking out the IR filter and placing a piece of exposed and processed film (an end of a negative)into that slot. I got a pure IR webcam. When looking at certain denominations of paper money you will see bands of missing ink as part of the money shows completely white.

At the risk of sounding foolish, these look like black and white shots to me. I’m not trying to be insulting or anything. Yes, I can see the difference, but the ‘color’ palette is the same, it seems–just reassigned. Am I missing something?

You can get a G5 for ~$100, and it’s a fine camera for this sort of work. Then you can either make your own replacement glass (the “Hiro Sandwich” on Don Ellis’ page, or buy a replacement from Lifepixel.

I’ve done several of these, some each way. If you go DIY, you need about another $20 in materials. If you buy the filter, you’re into it for about $200. In checking G5 prices on eBay, I also noticed a couple of G5s that are already converted for $250-300.

Then add an IR-pass filter of your choosing in front of the lens (G5 needs a cheap adapter to mount the filter) and you’re good to go with one of the best IR cameras out there.

The IR we’re talking about here is Near-IR, just outside the normal range of vision, where the appearance is based on how a surface reflects light. Most discussions of IR detection are about the wavelengths that measure the heat emitted by the object. So, Hiroken, you are right, it’s like adding one more color.

There’s also a difference between simple “IR” and thermal imaging. IR devices used to be routinely cooled with Cryo tech for dramatic sensitivity over other methods of the time. I am so far from an expert in IR compared to many folks here it’s not funny. But I do have hands on experience using IR thermometers for averting doom in several situations…. Which taught me there ARE differences in the IR sensing methods and application of them. Primarily in sensitivity and resolving gradients. The concept becomes more apparent in applications like energy audits.
Or that aforementioned checking electrical/mechanical items for impending failures. Yeah, you WILL see some glaringly obvious way out of safe ranges issues with these lower tech methods. Just be careful about a false sense of security from using gear not sensitive enough.

WeeGee the photographer took the best Infra -red photos of patrons in the movie houses in the
1940’s 1950’s making out ,Yup that’s where we old timers went.
No one saw the red flash bulb on his camera when he made those photo’s.If they did maybe they thought
it was cupid.

“…Wasn’t there a kerfuffle a few years ago re: infrared ability in a Sony camera? Something about pictures of people; a bit more detail of the body beneath the clothes showed through than you would expect… XRAY CAMS SNAP NUDE SHOTS the tv news talking heads foamed-at-the-mouth..?”

That was the official STATED reason. In order to make owning the camera a potential crime of being a “peeping Tom” pervert. That way they could get (nearly) all the camerasback. Of course the idea is ridiculous. To think that Sony never spotted this “problem” in the hundreds of hours of testing. The conspiracy reason is that these cameras were able to pick up UFO’s in the sky since they operate in a very extreme spectrum of infra-red. The government went bananas and they managed to suck back nearly all 5000 models.

(add.) If you’re wondering how they managed to get just about all the cameras back, the answer is point cards. The major electrical chains use 10-15%-of-value cards that must have all your details. Nearly everyone uses them for purchases… 15% of a $500 purchase is a lot of money! You can use the credits to knock off the price of the next item you buy. People who prefer more “extra personal” service and consequently buy from a small local store most likely had the staff fill out all the warranty details for them, thus recording their residence. Each registered buyer’s home was visited by staff and a full refund or exchange was given, no questions asked. A few weren’t returned and fell into the hands of the Yakuza who thought they had a new toy for their underground videos. But surprise, surprise… it didn’t seem to work as well as the News stations breathlessly flashed over the TV and those “blackmarket” models fell off the market after going for some extreme prices.

The reason foliage appears white is because it’s like snow — it’s transparent, but has air in it so it refracts and scatters the light and makes it look as if it’s glowing.

@15: Perhaps the image above isn’t the best example of near-IR because it appears they’re still letting some visible light in. But if you look on Wikipedia, you should see some that are more obviously different to a black and white photo. Although, I can still clearly see the difference in this one — you can’t duplicate that effect in Photoshop with a normal image.

Digital IR photography is not that hard to do, and does not require removing the IR filter if you are willing to use a tripod. A couple of layers of developed, exposed color slide film block out the visible light. I use an old Toshiba PDR M-81 digital camera, and set the focus to “closeup,” and pus a few layers of exposed color slide film in front of the lens. It works well, byut the exposures are about 1/4 of a second to 1 second, so I need to use a tripos.

I also do the same thing with a Canon EOS Rebel digital 30oD, which needs to be manually focused at a few feet and needs exposures of 1/2 second to 4 seconds.

Also, if you’re doing it with a tripod with a digital slr you’ll want to block off the viewfinder – visible light gets in and can leak into the body – Canon has a plug that goes on your strap that comes with some models, but I find I have to throw an opaque cloth over the camera a la 19th Century photography.